No, you don't have to leave feed in there, but it's easiest to just top off the bucket and give it a good stir every day. Most people seriously overthink the entire thing.
Bragg's will speed it slightly but it isn't very critical. I don't remember if it was Nzwered Bought feeding methods, but it is not free feeding. Give them enough to finish in ten or fifteen minutes. If you free range, only feed them in the evening. Otherwise, give them a serving morning and evening.
You've gotta record that hand feeding routine for us, 'cause it'll be hysterical. Nobody, I repeat NOBODY I have heard about has CALM chickens when it comes to the fermented feed, and they will always act hungry.
Any more questions I missed? It really is as simple as it sounds.